Access point in a wireless LAN

ABSTRACT

A wireless access device in a local area network (LAN) having a plurality of transceivers. Each transceiver has a directional antenna positioned in a substantially circular array to communicate signals with a plurality of stations in a corresponding sector. Each sector defines a portion of a coverage area surrounding the wireless access device. The wireless access device has a network interface to a data network, and an array controller to control communication of data between the stations and the transceivers, and between the transceivers and the network interface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to the provisional patent applications,Ser. No. 60/660,171, titled “WIRELESS LAN ARRAY,” by Dirk I. Gates, IanLaity, Mick Conley, Mike de la Garrigue, and Steve Smith, filed on Mar.9, 2005, and incorporated herein by reference; Ser. No. 60/660,276,titled “WIRELESS LAN ARRAY,” by Dirk I. Gates, Ian Laity, Mick Conley,Mike de la Garrigue, and Steve Smith, filed on Mar. 9, 2005, andincorporated herein by reference; Ser. No. 60/660,375, titled “WIRELESSACCESS POINT,” by Dirk I. Gates and Ian Laity, filed on Mar. 9, 2005,and incorporated herein by reference; Ser. No. 60/660,275, titled“MULTI-SECTOR ACCESS POINT ARRAY,” by Dirk I. Gates Ian Laity, MickConley, Mike de la Garrigue, and Steve Smith, filed on Mar. 9, 2005, andincorporated herein by reference; Ser. No. 60/660,210, titled “MEDIAACCESS CONTROLLER FOR USE IN A MULTI-SECTOR ACCESS POINT ARRAY,” by Mikede la Garrigue and Drew Bertagna filed on Mar. 9, 2005, and incorporatedherein by reference; Ser. No. 60/660,174, titled “QUEUE MANAGEMENTCONTROLLER FOR USE IN A MULTI-SECTOR ACCESS POINT ARRAY,” by Mike de laGarrigue and Drew Bertagna filed on Mar. 9, 2005, and incorporatedherein by reference; Ser. No. 60/660,394, titled “WIRELESS LAN ARRAY,”by Dirk I. Gates, Ian Laity, Mick Conley, Mike de la Garrigue, and SteveSmith, filed on Mar. 9, 2005, and incorporated herein by reference; Ser.No. 60/660,209, titled “WIRELESS LAN ARRAY ARCHITECTURE,” by Dirk I.Gates, Ian Laity, Mick Conley, Mike de la Garrigue, and Steve Smith,filed on Mar. 9, 2005, and incorporated herein by reference; Ser. No.60/660,393, titled “ANTENNA ARCHITECTURE OF A WIRELESS LAN ARRAY,” byAbraham Hartenstein, filed on Mar. 9, 2005, and incorporated herein byreference; Ser. No. 60/660,269, titled “LOAD BALANCING IN A MULTI-RADIOWIRELESS LAN ARRAY BASED ON AGGREGATE MEAN LEVELS,” by Mick Conley filedon Mar. 9, 2005, and incorporated herein by reference; Ser. No.60/660,392, titled “ADVANCED ADJACENT CHANNEL SECTOR MANAGE NT FOR802.11 TRAFFIC,” by Mick Conley filed on Mar. 9, 2005, and incorporatedherein by reference; Ser. No. 60/660,391, titled “LOAD BALANCING IN AMULTI-RADIO WIRELESS LAN ARRAY BASED ON AGGREGATE MEAN LEVELS,” by ShaunClem filed on Mar. 9, 2005, and incorporated herein by reference; Ser.No. 60/660,277, titled “SYSTEM FOR TRANSMITTING AND RECEIVING FRAMES INA MULTI-RADIO WIRELESS LAN ARRAY,” by Dirk I. Gates and Mike de laGarrigue, filed on Mar. 9, 2005, and incorporated herein by reference;Ser. No. 60/660,302, titled “SYSTEM FOR ALLOCATING CHANNELS IN AMULTI-RADIO WIRELESS LAN ARRAY,” by Dirk I. Gates and Kirk Mathews,filed on Mar. 9, 2005, and incorporated herein by reference; Ser. No.60/660,376, titled “SYSTEM FOR ALLOCATING CHANNELS IN A MULTI-RADIOWIRELESS LAN ARRAY,” by Dirk I. Gates and Kirk Mathews, filed on Mar. 9,2005, and incorporated herein by reference; Ser. No. 60/660,541, titled“MEDIA ACCESS CONTROLLER FOR USE IN A MULTI-SECTOR ACCESS POINT ARRAY,”by Dirk I. Gates and Mike de la Garrigue, filed on Mar. 9, 2005, andincorporated herein by reference; and PCT patent application serialnumber PCT/US2006/008747, titled “WIRELESS LOCAL AREA NETWORK ANTENNAARRAY,” filed on Mar. 9, 2006, and incorporated by reference herein; PCTpatent application serial number PCT/US2006/008696, titled “WIRELESSACCESS POINT,” filed on Mar. 9, 2006, which claims priority to the aboveprovisional patent applications, and incorporated by reference herein;PCT patent application serial number PCT/US2006/008744, titled “MEDIAACCESS CONTROLLER FOR USE IN A MULTI-SECTOR ACCESS POINT ARRAY,” filedon Mar. 9, 2006, and incorporated by reference herein; and PCT patentapplication serial number PCT/US2006/008698, titled “SYSTEM FORALLOCATING CHANNELS IN A MULTI-RADIO WIRELESS LAN ARRAY,” filed Mar. 9,2006, and incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to wireless data communication systems and moreparticularly to systems and methods for providing access points inwireless local area networks.

2. Description of the Related Art

The use of wireless communication devices for data networking is growingat a rapid pace. Data networks that use “WiFi” (“Wireless Fidelity”) arerelatively easy to install, convenient to use, and supported by the IEEE802.11 standard. WiFi data networks also provide performance that makesWiFi a suitable alternative to a wired data network for many businessand home users.

WiFi networks operate by employing wireless access points to provideusers having wireless (or ‘client’) devices in proximity to the accesspoint with access to data networks. The wireless access points contain aradio that operates according to one of three standards specified indifferent section of the IEEE 802.11 specification. Radios in accesspoints communicate using omni-directional antennas in order tocommunicate signals with wireless devices from any direction. The accesspoints are then connected (by hardwired connections) to a data networksystem that completes the users' access to the Internet.

The three standards that define the radio configurations are:

-   -   1. IEEE 802.11a, which operates on the 5 GHz band with data        rates of up to 54 Mbps;    -   2. IEEE 802.11b, which operates on the 2.4 GHz band with data        rates of up to 11 Mbps; and    -   3. IEEE 802.11g, which operates on the 2.4 GHz band with data        rates of up to 54 Mbps.

The 802.11b and 802.11g standards provide for some degree ofinteroperability. Devices that conform to 802.11b may communicate with802.11g access points. This interoperability comes at a cost as accesspoints will incur additional protocol overhead if any 802.11b devicesare connected. Devices that conform to 802.11a may not communicate witheither 802.11b or g access points. In addition, while the 802.11astandard provides for higher overall performance, 802.11a access pointshave a more limited range due to their operation in a higher frequencyband.

Each standard defines ‘channels’ that wireless devices, or clients, usewhen communicating with an access point. The 802.11b and 802.11gstandards each allow for 14 channels. In IEEE Std. 802.11a-1999, 200channels are defined; each channel centered every 5 MHz from 5000 MHz to6000 MHz. The 802.11a standard currently allows for 12 channels in theUS. The 14 channels provided by 802.11b and g include only 3 channelsthat are not overlapping. The 12 channels provided by 802.11a arenon-overlapping channels. The FCC is expected to allocate 11 additionalchannels in the 5.47 to 5.725 GHz band.

Access points provide service to a limited number of users. Accesspoints are assigned a channel on which to communicate. Each channelallows a recommended maximum of 64 clients to communicate with theaccess point. In addition, access points must be spaced apartstrategically to reduce the chance of interference, either betweenaccess points tuned to the same channel, or to overlapping channels. Inaddition, channels are shared. Only one user may occupy the channel atany give time. As users are added to a channel, each user must waitlonger for access to the channel thereby degrading throughput.

As more and more users utilize access points for service, there is aneed to increase the number of clients served by each access point andto maintain throughput even as the number of clients is increased.

SUMMARY

Systems consistent with the present invention provide wireless accessdevices for providing a plurality of client devices with wireless accessto at least one data network. In one example, the wireless accessdevices employ a plurality of transceivers, each transceiver having adirectional antenna. Each directional antenna is positioned to transmitand receive signals in a sector. Each sector defines a portion of acoverage area surrounding the wireless access device. The wirelessaccess device has an array controller connected to the plurality oftransceivers to control operation of the plurality of transceivers. Thewireless access device also has a network interface to a data networkand a media access controller to control communication of data betweenthe transceivers and the network interface.

Other systems, methods, features and advantages of the invention will beor will become apparent to one with skill in the art upon examination ofthe following figures and detailed description. It is intended that allsuch additional systems, methods, features and advantages be includedwithin this description, be within the scope of the invention, and beprotected by the accompanying claims.

BRIEF DESCRIPTION OF THE FIGURES

The components in the figures are not necessarily to scale, emphasisinstead being placed upon illustrating the principles of the invention.In the figures, like reference numerals designate corresponding partsthroughout the different views.

FIG. 1 is a block diagram of a network that uses a wireless accessdevice.

FIG. 2 is a block diagram of a transceiver module in the wireless accessdevice in FIG. 1.

FIG. 3 is a block diagram of a controller in the wireless access deviceshown in FIG. 1.

FIG. 4 is a diagram illustrating the formation of sectors by thewireless access device of FIG. 1.

FIGS. 5A-E are diagrams illustrating examples of coverage patternsformed by an example of the wireless access device of FIG. 1.

FIG. 6A is a diagram of a wireless access device of FIG. 1 labeled byradio type and number.

FIG. 6B shows coverage patterns formed by the different radio types onthe wireless access device.

FIG. 7 illustrates operation of a wireless access device.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of network 10 that uses a wireless accessdevice 100 to provide client devices (or “stations”), such as a laptopcomputer 20, access to data network services available on the Internet160. The wireless access device 100 is connected to a wired network 120,which may provide a connection to the Internet 160 or other network.Depending on the number of stations and the size of the area ofcoverage, the network 10 may include additional wireless access devices130. A network management system 120 may be used to configure and managethe wireless access devices 100, 130.

The wireless access device 100 in FIG. 1 has a substantially circularstructure 108 and includes a array controller 102, a plurality oftransceiver modules 110, and a network interface 114. The transceivermodules 110 contain one or more transceivers, radios, for example, andeach transceiver is connected to an antenna 112. The transceiver modules110 are also connected to the array controller 102, which operates toconfigure the transceiver modules 110 and manage any communicationsconnections involving the transceivers.

The wireless access device 100 shown in FIG. 1 has sixteen antennas 112.One of ordinary skill in the art will appreciate that any number ofantennas may be used. The antennas 112 that correspond to thetransceivers in the transceiver modules 110 are disposed near theperimeter of the substantially circular structure 108 of the wirelessaccess device 100. The antennas 112 are preferably directional antennasconfigured to transmit and receive signals communicated in a radialdirection from the center of the wireless access device 108. Eachantenna 112 covers a portion of the substantially circular areasurrounding the wireless access device 100 called a “sector” S_(i). Thetotal area covered by all of the sectors defines a 360° area of coverageof the wireless access device 100. This means that a station 20 locatedin a sector of the area of coverage would be able to communicatewirelessly with the antenna 112 corresponding with that sector.Multi-sector coverage is discussed in more detail below with referenceto FIGS. 5A-5E.

The network 10 in FIG. 1 implements well-known standards and protocolsused to communicate over the Internet 160. The transceivers in thewireless access device 100 in FIG. 1 communicate with stations 20 inaccordance with the IEEE 802.11 standard (802.11a, 802.11b, 802.11g),which is incorporated herein by reference. The remainder of thisspecification describes operation of examples of the wireless accessdevice 100 in the context of systems that implement IEEE 802.11a, b, org. However, the present invention is not limited to systems thatimplement any particular standard. The wireless access device 100 mayoperate according to any current or future standard, such as forexample, the forthcoming IEEE 802.11n.

The wireless access device 100 in FIG. 1 has four transceiver modules110. Each transceiver module 110 contains four transceivers, each ofwhich is programmable. In a preferred configuration, three of the fourtransceivers (shown in FIG. 1 with antennas labeled ‘a’) in eachtransceiver module 110 are designated to operate as 802.11a radios. Theremaining transceiver (shown in FIG. 1 with antenna labeled ‘abg’) maybe programmed to operate according to any of 802.11a, b, or g. Eachtransceiver is configured to operate on an assigned channel. The channelmay be one of the twelve channels available using the 802.11a standardor one of the fourteen channels available using the 802.11b/g standard.

The wireless access device 100 communicates with stations 20 wirelessly.The stations 20 may be any device enabled to communicate wirelessly withthe wireless access device 100 such as, without limitation, laptopcomputers, mobile telephones (for voice-over-LAN, or VOWLANapplications), personal digital assistants, handheld computers, etc. Inexamples described here, the stations are enabled to operate inaccordance with one or more of the 802.11 standards. When the station 20enters the coverage area of the wireless access device 100, it may senda request to connect to the access point 160. The wireless access device100 may perform an authentication process in a login session. Onceauthenticated, the user of the station 20 may be connected to theInternet 160.

FIG. 2 is a block diagram of a transceiver module 210 that may beimplemented in the wireless access device 100 shown in FIG. 1. Thetransceiver module 210 includes four radios, one of which is an ‘abg’radio 220 and three of which are ‘a’ radios 222. All four radios 220,222 include an amplifier 230, a radio signal processor 240, and abaseband processor 250. The four radios 220, 222 communicate with atransceiver module interface 260, which allows the transceiver module210 to communicate with the rest of the wireless access device. One ofordinary skill in the art will appreciate that four radios 220, 222 areshown as an example. The transceiver module 210 may also have one, two,or any number of radios.

Each radio 220, 222 connects to an antenna 212, which transmits andreceives radio signals received from the amplifier 230. As describedwith reference to FIG. 1, the antennas 212 are directional antennas,which concentrate signal power in one direction. Directional antennascan therefore cover greater distances than omni-directional antennasused in typical wireless access devices. The multiple radios withradially disposed directional antennas advantageously provides a 360°coverage pattern that is larger than that of radios withomni-directional antennas used in current access points.

The baseband processor 250 processes the digital data that is eitherbeing received or transmitted by the radio 220, 222. The basebandprocessor 250 implements protocols required for such functions asassembling/disassembling payloads. The baseband processor 250 performsthe digital functions required to implement the 802.11 standard.Preferably, the baseband processor 250 is programmable and may beconfigured for any of the three standards (802.11a, 802.11b, 802.11g).One example of a baseband processor 250 that may be implemented is theAgere WL64040.

The radio signal processor 240 modulates signals to be transmitted anddemodulates signals that have been received. The radio signal processor240 is preferably programmable to implement either the modulationschemes specified by 802.11b/g or 802.11a. One example of a radio signalprocessor 240 that may be implemented is the Agere WL54040.

The amplifier 230 generates the radio signal to be transmitted by thetransceiver 220, 222 and amplifies signals being received by the antenna212. One example of an amplifier that may be implemented in thetransceiver module 210 is the SiGe Semiconductor SE2535L for the 5 GHzor 802.11a radios, and the SiGe Semiconductor SE2525L for the 2.4 GHz or802.11b/g radios.

In the transceiver module in FIG. 2, the amplifier 230, radio signalprocessor 240, and/or baseband processor 250 may be programmable so thatthe array controller 102 (in FIG. 1) may control the transceiver module200 in a manner that provides certain features. For example, the arraycontroller 102 (in FIG. 1) may control the amplifiers 230 in a mannerthat makes the coverage pattern of the wireless access device 102 largeror smaller depending on the needs of the implementation. In addition,the baseband processor 250 may communicate information (such as signalstrength) about the radio connection between the wireless access device100 and the stations 20.

It is noted that the following description refers to transceivers asradios. Those of ordinary skill in the art will appreciate that the term“radio” is not intended as limiting the transceiver to any particulartype.

FIG. 3 is a block diagram of an array controller 300 that may beimplemented in the wireless access device 100 shown in FIG. 1. The arraycontroller 300 includes a processor 310, a packet and queue controller320, a medium access controller 330, a radio interface 340, and a datanetwork interface 350.

The processor 310 provides computing resources to the wireless accessdevice. The processor 310 may be any suitable custom or commercialmicroprocessor, microcontroller, computing chip or other type ofprocessor. The array controller 300 also includes supporting circuitryfor the processor 310 such as clock circuitry, I/O ports, memory(including Read Only Memory, or ROM, Random Access Memory, or RAM, Flashmemory, Programmable Rom or PROM, etc.), direct memory access, etc. Theprocessor 310 may also manage a bus system for communicating with itssupport circuitry and with the packet and queue controller 320, datanetwork interface 350 and medium access controller 330. In one example,the processor 310 is a Motorola 8540 800 MHz CPU supported by 64 MBexpandable system FLASH memory, 128 MB DDR 333 expandable system RAM,and a serial interface (RS232-RJ45 connector). An optional securityco-processor may also be included.

The data network interface 350 includes input/output circuitry forcommunicating over a data network. The array controller 300 implementsstandards and protocols that allow for communication over the Internet.The data network interface 350 preferably allows for the highestpossible speed connection. In one example, the data network interface350 includes primary and secondary Gigabit Ethernet interfaces, a FastEthernet interface, and failover support between the Gigabit Ethernetinterfaces.

The packet and queue controller 320 handles receiver and transmitterqueues, performs DMA functions, resolves fragmentation, and performspacket translation. The medium access controller 330 provides all IEEE802.11 MAC services for transceivers. For the wireless access device 100in FIG. 1, the medium access controller 330 provides 802.11 MAC servicesfor as many as sixteen transceivers. Both the packet and queuecontroller 320 and the medium access controller 330 are preferablyimplemented as application specific integrated circuits (ASIC).

The array controller 300 performs the programmed functions that controlthe wireless access device 100 as an access point. Functions andfeatures of the operations that the array controller 300 performsinclude:

-   -   1. General implementation IEEE 802.11 Access Point        functionality.    -   2. Non-blocking packet processing from/to any radio interface.        In typical wireless access devices that employ a single,        omni-directional radio, a packet that is being transmitted may        block other packets from access to the medium. This may occur in        either direction. Stations typically transmit packets to an        access point when the medium is not busy. If the medium is busy        with packets from other stations, for example, the packet is        blocked. Similarly, the access point may be attempting to send a        packet to a station. If other packets are being sent to another        station, the original packet is blocked from access to the        medium. In the wireless access device 100, when a station is        blocked from communicating a packet to one radio, it may switch        to another radio that is not blocked. If the wireless access        device 100 is blocked from sending a packet via one radio, it        may switch to another radio.    -   3. Dynamic automatic channel assignment. The array controller        300 implements algorithms and/or other schemes for assigning        channels of the 802.11 standards to the multiple radios.        Channels are allocated to radios in a manner that reduces        adjacent channel interference (ACI).    -   4. Directional awareness of where a wireless station is in        geographic relationship to the wireless access device 100. The        array controller 300 receives information such as signal        strength, and for each station, may keep track of how the signal        strength changes over time. In addition, even if one radio is        locked in and “connected” to a station, another radio may        receive signals and thus, “listen” to the station. The signal        strength in relation to the specific radios gathering signal        information provide the array controller with sufficient        information to create a directional awareness of the location of        the wireless station.    -   5. Station mobility services whereby a station can instantly        roam from one sector to another without requiring        re-authentication of the station. As a wireless station moves in        the coverage area space of the wireless access device, the        signal strength sensed by the array controller changes. As the        signal strength of the station becomes weaker, the radio        associated with the adjacent sector locks in and “connects” with        the station without requiring re-authentication.    -   6. Wireless quality of service.    -   7. Enhanced load balancing of wireless stations.    -   8. Constant RF monitoring of channel conditions and security        threats    -   9. Wireless Security processing    -   10. Internal Authentication Server. Typically, authentication        takes place at a server or router that is wired to the access        points. In the wireless access device 100, authentication may be        done by the array controller 300.    -   11. Wired Networking protocol support.    -   12. System failover handling and error handling. Because sectors        overlap, when a radio fails, the adjacent radios may lock in        with stations being handled by the failed radio. In some        examples of the wireless access device 100, the array controller        300 may increase power to adjacent sectors to ensure coverage in        any area covered by the failed sector. In addition, when        multiple access devices are deployed, one wireless access device        may increase power and expand a sector to cover area left        without service when a radio fails in an adjacent wireless        access device.    -   13. System management functions.

As discussed above, examples of wireless access devices and systems thatemploy wireless access devices described in this specification (withoutlimitation) operate in the wireless LAN environment established by theIEEE 802.11 standardization body. The IEEE 802.11 standards including(without limitation):

-   -   IEEE 802.11, 1999 Edition (ISO/IEC 8802-11: 1999) IEEE Standards        for Information Technology—Telecommunications and Information        Exchange between Systems—Local and Metropolitan Area        Network—Specific Requirements—Part 11: Wireless LAN Medium        Access Control (MAC) and Physical Layer (PHY) Specifications    -   IEEE 802.11a-1999 (8802-11:1999/Amd 1:2000(E)), IEEE Standard        for Information technology—Telecommunications and information        exchange between systems—Local and metropolitan area        networks—Specific requirements—Part 11: Wireless LAN Medium        Access Control (MAC) and Physical Layer (PHY)        specifications—Amendment 1: High-speed Physical Layer in the 5        GHz band    -   IEEE 802.11b-1999 Supplement to 802.11-1999, Wireless LAN MAC        and PHY specifications: Higher speed Physical Layer (PHY)        extension in the 2.4 GHz band    -   802.11b-1999/Cor1-2001, IEEE Standard for Information        technology—Telecommunications and information exchange between        systems—Local and metropolitan area networks-Specific        requirements—Part 11: Wireless LAN Medium Access Control (MAC)        and Physical Layer (PHY) specifications—Amendment 2:        Higher-speed Physical Layer (PHY) extension in the 2.4 GHz        band—Corrigendum1    -   IEEE 802.11d-2001 Amendment to IEEE 802.11-1999, (ISO/IEC        8802-11) Information technology—Telecommunications and        information exchange between systems—Local and metropolitan area        networks—Specific requirements—Part 11: Wireless LAN Medium        Access Control (MAC) and Physical Layer (PHY) Specifications:        Specification for Operation in Additional Regulatory Domains    -   IEEE 802.11F-2003 IEEE Recommended Practice for Multi-Vendor        Access Point Interoperability via an Inter-Access Point Protocol        Across Distribution Systems Supporting IEEE 802.11 Operation    -   IEEE 802.11g-2003 IEEE Standard for Information        technology—Telecommunications and information exchange between        systems—Local and metropolitan area networks—Specific        requirements—Part 11: Wireless LAN Medium Access Control (MAC)        and Physical Layer (PHY) specifications—Amendment 4: Further        Higher-Speed Physical Layer Extension in the 2.4 GHz Band    -   IEEE 802.11h-2003 IEEE Standard for Information        technology—Telecommunications and Information Exchange Between        Systems—LAN/MAN Specific Requirements—Part 11: Wireless LAN        Medium Access Control (MAC) and Physical Layer (PHY)        Specifications: Spectrum and Transmit Power Management        Extensions in the 5 GHz band in Europe    -   IEEE 802.11i-2004 Amendment to IEEE Std 802.11, 1999 Edition        (Reaff 2003). IEEE Standard for Information        technology—Telecommunications and information exchange between        system—Local and metropolitan area networks Specific        requirements—Part 11: Wireless LAN Medium Access Control (MAC)        and Physical Layer (PHY) specifications—Amendment 6: Medium        Access Control (MAC) Security Enhancements    -   IEEE 802.11j-2004 IEEE Standard for Information        technology—Telecommunications and information exchange between        systems—Local and metropolitan area networks—Specific        requirements—Part 11: Wireless LAN Medium Access Control (MAC)        and Physical Layer (PHY) specifications—Amendment 7: 4.9 GHz-5        GHz Operation in Japan        All of the above-listed standards are incorporated herein by        reference.

Radios operating under 802.11 may operate in one of two frequency bands:the 2.4 GHz band and the 5 GHz band. The IEEE specifies multiplechannels within each band (see Table 1). Channels are defined asallocations of frequency spectrum with specified center frequencies andspacing. For example, in the 2.4 GHz band there are 14 defined channelsstarting at a center frequency of 2.412 GHz and incrementing up to 2.484GHz at 5 MHz intervals. Channels are considered overlapping if theirbands overlap above a certain power threshold. For instance, in the 2.4GHz region each channel operates with a frequency band of 12 MHz oneither side of the center frequency. So with 14 channels defined withcenter frequencies 5 MHz apart, several of them are overlapping. Infact, there are only three channels (channels 1, 6, and 11) that do notoverlap in the 2.4 GHz band. Their center frequencies are 2.412 GHz,2.437 GHz and 2.462 GHz.).

In the 5 GHz band, the IEEE Std. 802.11a-1999 defines 200 channels; eachchannel centered every 5 MHz from 5000 MHz to 6000 MHz. The 802.11astandard currently allows for 12 channels in the US. The 12 channelsprovided by 802.11a are non-overlapping channels. The FCC is expected toallocate 11 additional channels in the 5.47 to 5.725 GHz band. Those ofordinary skill in the art will appreciate that the channels describedherein are for purposes of illustrating an example and not intended asany limitation on the scope of the invention. Embodiments of the presentinvention that are designed to implement any part of the 802.11 standardmay use any set of channels specified by any part of the IEEE 802.11standard whether such channels are available now or in the future.

TABLE 1 IEEE 802.11 U.S. Radio Channel Assignments IEEE 802.11 A IEEE802.11 B/G (5.0 GHz Band) (2.4 GHz Band) Channel Frequency ChannelFrequency Number (MHz) Number (MHz) 36 5180 1 2412 40 5200 2 2417 445220 3 2422 48 5240 4 2427 52 5260 5 2432 56 5280 6 2437 60 5300 7 244264 5320 8 2447 149 5745 9 2452 153 5765 10 2457 157 5785 11 2462 1615805 12 2467 13 2472 14 2484

The wireless access device 100 in FIG. 1 assigns channels to the sixteenradios in a manner that enhances performance, throughput, coverage areaand capacity. Typical access points use one radio with a coverage areadefined by an omni-directional antenna and assigned to a single channel.Therefore, all of the users in the coverage area tune in to the samechannel in order to communicate with the access point. In the wirelessaccess device 100 in FIG. 1, each radio forms a different sectordefining a portion of a substantially circularly-defined coveragepattern. In addition, each radio is assigned a unique channel so that notwo radios in one device communicate over the same channel.

FIG. 4 is a diagram illustrating the formation of sectors by thewireless access device of FIG. 1. The wireless access device 100 has 16radios 412 divided into groups of four radios 412 mounted on each offour transceiver modules 410. An array controller 402 is located roughlyin the center of the wireless access device 100 where it connects witheach of the four transceiver modules 410 at inter-module connections408. The inter-module connections 408 contain communication paths (via abus or set of signal paths on a connector) that implement the interfacebetween the array controller 402 and the radios 412. One of ordinaryskill in the art will appreciate that the wireless access device 100 mayhave more or fewer than 16 radios. For example, in other embodiments,the wireless access device 100 has 4 radios (e.g. three ‘abg’uni-directional radios and one ‘abg’ omni-directional) or 8 radios (e.g.four ‘a’ unidirectional radios, three ‘abg’ unidirectional radios, one‘abg’ omni-directional radio) or even 24 radios (anywhere from 16-24 ‘a’radios and 0-8 ‘abg’ radios). The number of radios is not important solong as multiple radios may be configured to provide a 360° coveragearea.

As discussed, each radio 412 contains a directional antenna configuredto establish a coverage area in a sector 450 that radiates out from thewireless access device 100. The radios 412 may be individuallycontrolled such that when they are all operating they may form acoverage pattern that surrounds the wireless access device 100. Thecoverage pattern created by the wireless access device 100 may besimilar to coverage patterns created by existing access points that useone radio radiating out of an omni-directional antenna. However, thewireless access device 100 in FIG. 4 uses sixteen radios 412 radiatingout of more powerful directional antennas to create a coverage patternarea that is significantly greater than that of a typical access point.In addition, the sectors 450 created by the radios 412 in the wirelessaccess device 100 advantageously overlap to provide features notcurrently available in typical access points. The radios 412 are alsoprogrammable such that they may be controlled to operate at power levelsthat allow for coverage patterns that are suited to the layout of theimplementation. Examples are discussed below with reference to FIGS.5A-E.

In FIG. 5A, a wireless access device 100 is implemented in animplementation I with all of the radios in the wireless access device100 configured to communicate with stations within a coverage area 502.The radios in the wireless access device 100 form sectors. A firstsector 530 is shown with an adjacent sector 540 along with an area ofoverlap 550 formed by the overlap of the first and second sectors 530,540. FIG. 5A illustrates one of many advantages that the wireless accessdevice 100 has over typical access points. The wireless access device100 includes programmable and configurable control over the operation ofthe radios on the wireless access device 100. When deployed, thewireless access devices 100 may be configured to create a coveragepattern that is suitable for by the exact implementation I. For example,in FIG. 5A, the coverage pattern 502 has been configured to conform tothe implementation I. The wireless access device 100 may be configuredsuch that the radios that create a set of coverage patterns 522, 524,526, 528, 530 that project towards a side 580 communicate signals at alower power limiting the extent of the coverage area created by eachradio. This is illustrated by a set of middle sectors 524, 526, 528covering less distance than outer sectors 522, 530, which cover thecorners or the implementation I along the side 580. This implementationI advantageously substantially limits the ability for a station toconnect from beyond the wall along the side 580 of implementation I.

FIG. 5B illustrates how the wireless access device 100 may be configuredto provide special features in a specific implementation. In FIG. 5B,the wireless access device 100 is implemented in a space 570 in whichthe resident desires to have wireless Internet access. The space 570 islocated with one side 590, which faces an open and public area fromwhich hackers or otherwise unauthorized users may attempt to gain accessto the Internet via the wireless access device 100. The wireless accessdevice 100 may be used to provide users in the space 570 with access tothe Internet while limiting access by those on the other side of 590.One way as illustrated in FIG. 5B is to place the wireless access device100 along the side 590 and turn off radios that would create sectors onthe other side of 590, and turn on the radios that create sectors in thespace 570. Such an implementation would yield a coverage pattern similarto the one shown in FIG. 5B.

FIG. 5C shows how the wireless access device 100 may be configured tolimit the affects of obstacles that may cause reflections in the radiosignals. Reflections in typical access points may cause multi-pathinterference. When radio signals reflect off of obstacles, thereflections may reach the station as different signals coming fromdifferent directions, or multiple paths. The wireless access device 100may be configured to avoid multi-path interference by configuring theradios to avoid generating sectors that could reach the obstacle. InFIG. 5C, the wireless access device 100 is shown generating sectors 520,540, but not generating any sectors in the direction of obstacle 575.

FIG. 5D illustrates how overlapping sectors may be used to provide radiofrequency failover so that stations do not lose connectivity when aradio fails, or is otherwise unavailable. In FIG. 5D, wireless accessdevice 100 has three radios creating a sector each (R1, R2, R3). In FIG.5E, the wireless access device 100 has lost the radio associated withsector R2. However, sectors R1, R2, R3 advantageously overlap. Thewireless access device 100 may switch stations in sector R2 that wereconnected via the radio that generated sector R2 to the radios thatcreated either of sectors R1 or R3.

FIG. 6A is a diagram of a wireless access device 100 of FIG. 1 labeledby radio type and number. Radios that communicate, or are configured tocommunicate, as 802.11a radios only are labeled ‘a.’ Radios that may beprogrammed or configured to communicate using 802.11a, b, or g radiosare labeled ‘abg.’ The twelve ‘a’ radios 610 (a1-a12) are assigned aunique one of the twenty-three channels available under the 802.11astandard. Three of the four ‘abg’ radios are assigned the threenon-overlapping channels available under the 802.11b/g standards. Thefourth ‘abg’ radio is implemented as an omni-directional radio in listenmode exclusively.

FIG. 6B shows coverage patterns formed by the different radio types onthe wireless access device. The twelve ‘a’ radios 610 each have acoverage area emanating in a sector that spreads out more than 30°. Thesectors of the twelve ‘a’ radios 610 may combine to form a substantiallycircular 802.11a coverage pattern 620. Preferably, the sectors arelarger than 30° in order to create overlap between the sectors, such asfor example, the overlap 650 between sectors 630 and 640. FIG. 6B alsoshows the three ‘abg’ radios 611 with the coverage area of more than120°. The sectors combine to provide a 360° coverage pattern. However,each sector is more than 120° to create overlap between the sectors. Thefourth ‘abg’ radio 613 is configured as an omni-directional radio ableto communicate in all directions. The fourth ‘abg’ radio 613 is used asa monitor or a sniffer radio in a listen-only mode. This radio listensto each channel in sequence to build a table of all stations and accessdevices. This table may be compared to an administrator controlled listof allowed stations and access devices. Stations and access devices notin the administrator controlled list are termed rogues. One functionperformed by the fourth ‘abg’ radio 613 is to detect unauthorizedstations in the coverage area.

FIG. 7 is a diagram of a wireless access device 700 connected wirelesslyto a plurality of stations 720 a-o via channels allocated to theplurality of radios a1-a12, afg1-afg4 on the wireless access device 700.The radios are labeled according to their type and radio numbers. Insidethe circles representing the radios are numbers identifying the channelsassigned to the radio. As shown, radios a1-a12 and afg1-afg4 areassigned channels as shown in Table 2 below:

TABLE 2 Radio No. Channel Frequency (MHz) A9 36 5180 A12 40 5200 A3 445220 A6 48 5240 A10 52 5260 A1 56 5280 A4 60 5300 A7 64 5320 A11 1495745 A2 153 5765 A5 157 5785 A8 161 5805 M — Monitor radio that canlisten on any abg channel abg1 1 2412 abg3 6 2437 abg4 11 2462

The radios in the wireless access device 700 are advantageously assigneddifferent channels. The radios in FIG. 7 and the array controller(described above with reference to FIG. 3) are housed within a singleenclosure tightly coupled by digital bus. The housing provides a centralcontrol point for the sixteen radios that is not tethered by any cabledbus.

The stations 720 a-o in FIG. 7 represents stations attempting to connectto the wireless access device 700. The arrows indicate the stations'ability to connect to a particular radio as well as the ability of thestation to communicate using the appropriate protocol (i.e. 802.11a, b,or g). To illustrate, station 720 a is a target wireless clientattaching to the wireless access device 700 using protocols specified by802.11a. Radios a5, a6, and a7 generate sectors that preferably overlapsuch that station 720 a may connect to either one of the three radios.Each radio is assigned a unique channel that does not overlap with anyother channel.

If the radio to which station 720 a fails, or is otherwise unable toprovide service to station 720 a, the array controller is able to switchthe connection to station 720 a over to one of the adjacent radios. TheIEEE 802.11a, b, and g protocols permit radios to “listen” to signalsbeing communicated with stations that are connected to another radio.The array controller may obtain data such as signal strength anddirectional awareness and other factors that allow it to determine whichradio is best suited to continue communicating with the station 720 a.

The wireless access device 700 is connected to a Gigabit Ethernet port780, which provides a direct connection to the user's network.

Although the controller 300 depicted in FIG. 3 uses memory, one skilledin the art will appreciate that a substantial part of systems andmethods consistent with the present invention may be stored on or readfrom other machine-readable media, for example, secondary storagedevices such as hard disks, floppy disks, and CD-ROMs; a signal receivedfrom a network; or other forms of ROM or RAM either currently known orlater developed. Further, although specific components of wirelessaccess device 100 are described, one skilled in the art will appreciatethat a network access device suitable for use with methods, systems, andarticles of manufacture consistent with the present invention maycontain additional or different components.

The foregoing description of an implementation has been presented forpurposes of illustration and description. It is not exhaustive and doesnot limit the claimed inventions to the precise form disclosed.Modifications and variations are possible in light of the abovedescription or may be acquired from practicing the invention. Forexample, the described implementation includes software but theinvention may be implemented as a combination of hardware and softwareor in hardware alone. Note also that the implementation may vary betweensystems. The claims and their equivalents define the scope of theinvention.

1. A wireless access device comprising: a plurality of transceivers,each transceiver having a directional antenna, each directional antennapositioned in a substantially circular array to communicate signals witha plurality of stations in a corresponding sector, each sector defininga portion of a coverage area surrounding the wireless access device; anetwork interface to a data network; and an array controller to controlcommunication of data between the stations and the transceivers, andbetween the transceivers and the network interface, the array controllerincluding coverage pattern defining functions operable to control thetransceivers to generate coverage patterns that provide access to aborder beyond which access is limited, and to generate coverage patternsthat limit reflections of signals off of an obstacle.
 2. A wirelessaccess device according to claim 1 where each of the plurality oftransceivers is a radio that may be configured to communicate pursuantto the IEEE 802.11a, IEEE 802.11b, IEEE 802.11g or any sub-part of IEEE802.11.
 3. A wireless access device according to claim 2 where theplurality of transceivers covers all available channels in the banddefined by IEEE 802.11b, or IEEE 802.11g.
 4. A wireless access deviceaccording to claim 2 where the plurality of transceivers covers allavailable channels in the band defined by IEEE 802.11a.
 5. A wirelessaccess device according to claim 2 where the transceivers include afirst plurality of transceivers configured to operate pursuant to IEEE802.11a and a second plurality of transceivers configured to operatepursuant to IEEE 802.11b/g.
 6. A wireless access device according toclaim 5 where each of the first plurality of transceivers is assigned aunique channel defined by 802.11a.
 7. A wireless access device accordingto claim 5 where each of the second plurality of transceivers isassigned a unique non-overlapping channel defined by 802.11b/g.
 8. Awireless access device according to claim 2 where one of the pluralityof transceivers is configured to receive only using an omni-directionalantenna.
 9. A wireless access device according to claim 1 where theplurality of transceivers includes: twelve 802.11a radios configured togenerate a uni-directional sector of at least 30′; three 802.11a/b/gradios configured to generate a uni-directional sector of at least 120°;and one 802.11a/b/g radio configured to generate an omni-directionalcoverage pattern.
 10. A wireless access device according to claim 1where the plurality of transceivers includes: four 802.11a radiosconfigured to generate a uni-directional sector of at least 90°; three802.11a/b/g radios configured to generate a uni-directional sector of atleast 120°; and one 802.11a/b/g radio configured to generate anomni-directional coverage pattern.
 11. A wireless access deviceaccording to claim 1 where the plurality of transceivers includes: three802.11a/b/g radios configured to generate a uni-directional sector of atleast 120°; and one 802.11a/b/g radio configured to generate anomni-directional coverage pattern.
 12. A system for providing access todata network services comprising: at least one wireless access devicehaving a plurality of transceivers, each transceiver having adirectional antenna, each directional antenna positioned in asubstantially circular array to communicate signals with a plurality ofstations in a corresponding sector, each sector defining a portion of acoverage area surrounding the wireless access device, the at least onewireless device including coverage pattern defining functions performedby enabling and disabling selected transceivers, where the coveragepattern defining functions are configured to control the transceivers togenerate coverage patterns that provide access to a border beyond whichaccess is limited and to generate coverage patterns that limitreflections of signals off of an obstacle; and a wired network connectedto the at least one wireless access device, the wired network having aninterface to at least one data network service; where the at least onewireless access device communicates with stations within the coveragearea and forms a communications path between the wireless stations andthe wired network.
 13. A system according to claim 12 where each of theplurality of transceivers in the at least one wireless access device isa radio configured to communicate pursuant to the IEEE 802.11a, IEEE802.11b, or IEEE 802.11g standard.
 14. A system according to claim 13where the plurality of transceivers in the at least one wireless accessdevice covers all available channels in the band defined by IEEE802.11b, or IEEE 802.11g.
 15. A system according to claim 13 where theplurality of transceivers in the at least, one wireless access devicecovers all available channels in the band defined by IEEE 802.11a.
 16. Asystem according to claim 13 where the transceivers in the at least onewireless access device include a first plurality of transceiversconfigured to operate pursuant to IEEE 802.11a and a second plurality oftransceivers configured to operate pursuant to IEEE 802.11b/g.
 17. Asystem according to claim 16 where each of the first plurality oftransceivers is assigned a unique channel defined by 802.11a.
 18. Asystem according to claim 16 where each of the second plurality oftransceivers is assigned a unique non-overlapping channel defined by802.11b/g.
 19. A system according to claim 12 where one of the pluralityof transceivers is configured to receive only using an omni-directionalantenna.
 20. A system according to claim 12 where the plurality oftransceivers includes: twelve 802.11a radios configured to generate auni-directional sector of at least 30′; three 802.11a/b/g radiosconfigured to generate a uni-directional sector of at least 120°; andone 802.11a/b/g radio configured to generate an omni-directionalcoverage pattern.
 21. A system according to claim 12 where the pluralityof transceivers includes: four 802.11a radios configured to generate auni-directional sector of at least 90°; three 802.11a/b/g radiosconfigured to generate a uni-directional sector of at least 120°; andone 802.11a/b/g radio configured to generate an omni-directionalcoverage pattern.
 22. A system according to claim 12 where the pluralityof transceivers includes: three 802.11a/b/g radios configured togenerate a uni-directional sector of at least 120°; and one 802.11a/b/gradio configured to generate an omni-directional coverage pattern.
 23. Asystem according to claim 12 further comprising a network managementsystem operable to provide management functions over the at least onewireless access device.